Bryan Caplan  

Pinker's Genome

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Steven Pinker answered the call to "know thyself" by having his genome sequenced.  Some results:

The two biggest pieces of news I got about my disease risks were a 12.6 percent chance of getting prostate cancer before I turn 80 compared with the average risk for white men of 17.8 percent, and a 26.8 percent chance of getting Type 2 diabetes compared with the average risk of 21.9 percent. Most of the other outcomes involved even smaller departures from the norm...

[...]

Direct-to-consumer companies are sometimes accused of peddling "recreational genetics," and there's no denying the horoscopelike fascination of learning about genes that predict your traits. Who wouldn't be flattered to learn that he has two genes associated with higher I.Q. and one linked to a taste for novelty? ...Then there are the genes for traits that seem plausible enough but make the wrong prediction about how I live my life, like my genes for tasting the bitterness in broccoli, beer and brussels sprouts (I consume them all), for lactose-intolerance (I seem to tolerate ice cream just fine) and for fast-twitch muscle fibers (I prefer hiking and cycling to basketball and squash). I also have genes that are nothing to brag about (like average memory performance and lower efficiency at learning from errors), ones whose meanings are a bit baffling (like a gene that gives me "typical odds" for having red hair, which I don't have), and ones whose predictions are flat-out wrong (like a high risk of baldness).
Pinker follows up with some interesting observations what he calls "Geno's Paradox":

Individual genes are just not very informative. Call it Geno's Paradox. We know from classic medical and behavioral genetics that many physical and psychological traits are substantially heritable. But when scientists use the latest methods to fish for the responsible genes, the catch is paltry.

Take height. Though health and nutrition can affect stature, height is highly heritable... Height should therefore be a target-rich area in the search for genes, and in 2007 a genomewide scan of nearly 16,000 people turned up a dozen of them. But these genes collectively accounted for just 2 percent of the variation in height, and a person who had most of the genes was barely an inch taller, on average, than a person who had few of them. If that's the best we can do for height, which can be assessed with a tape measure, what can we expect for more elusive traits like intelligence or personality?
Read the whole thing.


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COMMENTS (4 to date)
Mr. Econotarian writes:

One challenge to detecting heritable traits is that they may be due to epigentetic factors rather than pure DNA sequence. Until we have a good way of "reading" the epigenetic controls on expression of genes, we will miss these.

http://en.wikipedia.org/wiki/Epigenetics

Isaac K. writes:

The genetic heritability of height may be well known, but it is an extremely complex set of mechanisms.
Bone density, muscle build, childhood weight and activity, and a variety of factors all VASTLY impact height - it isn't a single variable.
Keep in mind that someone can have a genetically long torso and shorter than average legs - random variations in length of multiple factors will, at some point, average out.

The other issues discussed are considerably smaller and non-composite: hair and eye color occupy only a few genes.
Insulin production and other factors influence your heritable tendency towards diabetes - all genetically measurable.
High cholesterol and blood pressure are often known to be genetic.

Sensitivities to a particular taste or somesuch (bitterness, as mentioned) are much less complex and clearer than the "obvious" case of height.

Intellegence and personality are, similarly, composites of a variety of factors, physiological, emotional, psychological, and nutritional.
You can alter a personality chemically with drugs, or change it completely by treating vision problems.

The question becomes; is it conceptually sound to use the genotype of a child to learn what individual strengths they might possess and tailor treat them to maximize strengths and minimize weaknesses?
This could be structured somewhat similar to personality profiling to portray where persons of similar characteristics are found to excel occupationally.

Dr. T writes:

The Human Genome projects was almost as wasteful of money as the latest European super collider project. Looking for specific genes linked to conditions known to be heritable (such as cystic fibrosis or Tay Sachs disease) makes sense clinically and economically. Dredging through the entire genome looking for snippets of code that might be related to some characteristic or condition is clinically useless and economically wasteful.

Isaac K. mentions diabetes, hypercholesterolemia, and hypertension as genetic disorders. Adult onset diabetes has over 100 known causes, and only a few of them involve a single gene mutation. Common hypercholesterolemia also is polygenetic (unlike the rare familial forms that are due to a single gene mutation). Hypertension sometimes is genetic, but, usually not from a single gene mutation.

We still don't know enough about variable gene expression, polygenetic disorders, environmental affects on gene expression and genetic diseases, etc. Until we do, the type of genetic profile obtained by Pinker is little better than an astrological reading.

Troy Camplin writes:

His "oddities' only point out the incredible importance of epigenetics and the interactions between genes and environment. We have been learning more and more that one-gene, one-trait is incredibly rare at best. Combinations of genes and their locations on the genome itself are important, as well as snRNAs and RNA editing, among other things. RNA editing alone could completely change genes so that they create something other than what you think they are through simple sequencing.

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